当我尝试运行时apt-get update，遇到了奇怪的失败。
$sudo apt-get update
Ign:1 http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64 InRelease
Hit:2 http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64 Release
Hit:3 http://archive.ubuntu.com/ubuntu focal InRelease
Hit:5 https://nvidia.github.io/libnvidia-container/stable/ubuntu18.04/amd64 InRelease
Hit:6 https://nvidia.github.io/nvidia-container-runtime/stable/ubuntu18.04/amd64 InRelease
Hit:7 http://archive.ubuntu.com/ubuntu focal-updates InRelease
Hit:8 https://nvidia.github.io/nvidia-docker/ubuntu18.04/amd64 InRelease
Hit:9 http://security.ubuntu.com/ubuntu focal-security InRelease
Hit:10 http://archive.ubuntu.com/ubuntu focal-backports InRelease
Ign:11 https://packagecloud.io/segment/aws-okta/ubuntu focal InRelease
Err:12 https://packagecloud.io/segment/aws-okta/ubuntu focal Release
404 Not Found [IP: 54.215.161.51 443]
Reading package lists... Done
E: The repository 'https://packagecloud.io/segment/aws-okta/ubuntu focal Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
sources.list 文件看起来没问题：
# cat /etc/apt/sources.list.d/segment_aws-okta.list
# this file was generated by packagecloud.io for
# the repository at https://packagecloud.io/segment/aws-okta
deb https://packagecloud.io/segment/aws-okta/ubuntu/ focal main
deb-src https://packagecloud.io/segment/aws-okta/ubuntu/ focal main